1. Field of the Invention
The present invention relates to a method of and an apparatus for processing image data representing an original image including plural image regions, and more particularly to a technique to produce overlapping regions on the boundary of the plural image regions in the original image.
2. Description of the Related Art
In ordinary color printing, four primary color inks, that is, yellow, magenta, cyan, and black (YMCK), are applied to a printing paper with four printing plates.
Although the color printing machine has high accuracy and precision, misalignment of the printing plates, Which is between plus and minus about 0.05 is inevitable in actual printing. The misalignment, in many cases, causes undesirable blank regions or dropouts, thus lowering the quality of the printed matter.
In order to prevent the quality deterioration due to the misalignment of the printing plates, so-called `overlapping` process is executed. The overlapping process modifies the shapes of two adjacent image regions and creates an overlapping region on the boundary of adjacent image regions so that the adjacent image regions partially overlap with each other on the boundary. The color of the overlapping region is selected on the basis of the adjacent image regions to make the overlapping region unobtrusive.
However, it is not always easy to determine the shape of the overlapping region, especially for an image including a large number of image regions where many overlapping regions are to be made and where the boundaries of the overlapping regions are complicated.
An improved overlapping technique therefore has been strongly demanded which can determine the shape of each overlapping region by relatively simple steps. In order to attain the improved overlapping technique, it has been desired to develop a technique to easily produce additional regions, which are to be overlapping regions, on the boundaries of image regions.